Presently, the mobile phone networking systems tend to increase their communication bandwidth continuously, for example, the 3G and 4G mobile phone network. The providers of mobile phone service/content tend to increase the size of data/service such as video-on-demand and video-conferencing in order to fully utilize the abundant bandwidth provided by the mobile phone networking system, and the manufacturers of the mobile phones tend to increase the computation power of the mobile phones in order to decode the bandwidth-hungry content provided by the providers.
In most situations, however, a user 10 may only require a small amount of information, thus more cost-effective and low data-rate communication is sufficient. In the event that the user 10 enters a particular location, such as a shop or a restaurant which is located within a larger establishment, such as a shopping-mall, a hotel, or a car parking facility, the required data-rate bandwidth for information retrieval may be substantially reduced, and a sensor network 800 may be well-suited for this kind of application.